Core Technical Specifications to Define

You need to define the following parameters to create a complete specification sheet.

1. Capacity / Flow Rate (The Most Critical Spec)

This defines the range of gas flow the meter can handle accurately.

Maximum Flow Rate (Qmax): The highest flow rate at which the meter will operate without exceeding the maximum permitted error. It must be higher than your peak demand.

Normal Flow Rate (Qn or Qnom): A reference value for the meter's normal operating range. Often used for rating and comparison.

Minimum Flow Rate (Qmin): The lowest flow rate at which the meter will operate within its stated accuracy. Important for detecting small leaks or pilot lights.

How to Specify It:

Calculate your total gas load in BTU/h or kW.

Convert this to a volumetric flow rate (Cubic Feet per Hour - CFH or Cubic Meters per Hour - m³/h).

*For Natural Gas: CFH = Total BTU/h ÷ 1,030*

*Example: 200,000 BTU/h ÷ 1,030 ≈ 194 CFH*

Select a meter whose Qmax is greater than your calculated peak flow. Add a safety margin of 15-25% for future expansion.

In this case, a meter with a Qmax of 250 CFH(7.08m³/h） or 275 CFH （7.79m³/h）would be appropriate.

2. Gas Type and Properties

The meter must be built and calibrated for the specific gas.

Gas Family: Natural Gas (Methane), LPG (Propane), Butane, or Biogas.

Density: The mass per unit volume (e.g., kg/m³).

Calorific Value: The energy content (e.g., BTU/cf, kWh/m³). This is critical for energy metering.

3. Operating Pressure

Maximum Working Pressure (PSI or kPa): The highest pressure the meter's body and seals are designed to withstand safely.

Operating Pressure Range: The range of pressures the meter will experience in your system. Appliance regulators typically require 3.5" WC for natural gas, but the inlet pressure from the street can be higher (e.g., 0.25-2 PSI or "low pressure" or 2 PSI+ for "high pressure" systems).

4. Accuracy Class

This defines how precise the meter is over its flow range. It's expressed as a percentage (e.g., ±1.0%).

Class 1.5: Standard for most residential and commercial billing.

Class 1.0: Higher accuracy, often required for industrial or large commercial applications where small errors represent significant cost.

5. Size and Connections

Inlet/Outlet Size: The pipe thread size (e.g., 3/4" NPT, 1" NPT, 25mm, 32mm). It must match your existing piping.

Connection Type: The thread standard (e.g., NPT - National Pipe Taper, BSP - British Standard Pipe).

6. Environmental Conditions

Temperature Class: The ambient temperature range the meter is rated for (e.g., -20°C to +40°C).

Location: Is it for indoor or outdoor installation? Outdoor meters may need better weatherproofing.

7. Meter Type (Technology)

Based on your flow rate and application, specify the technology.

Diaphragm (Positive Displacement): AC-175, AC-250, AC-1000. Best for steady, low-to-medium flows.

Rotary/Turbine: Best for higher, more fluctuating flows.

Ultrasonic: Best for high accuracy, wide flow range, and no moving parts.

8. Additional Features (Optional but Important)

Index / Register: Mechanical dial or digital display. Digital is easier to read and can offer more data.

Pulse Output: Allows connection to energy monitoring systems.

Communication Protocol: For "smart" meters (AMR/AMI). Defines how the meter transmits data (e.g. LoRaWAN).

Temperature Compensation: Adjusts the volume reading to a standard temperature (e.g., 15°C). Crucial for fair billing in regions with significant temperature swings. Pressure Correction: Built-in pressure sensor to correct volume to standard pressure.